olfart Posted March 27, 2016 Share Posted March 27, 2016 I've just completed my first propane forge using firebrick and a Guru's burner. I filed a slight flare in the burner opening in the firebrick and mounted the burner tube at the top of the flare. I've not yet figured out why I'm getting an intermittent flame. It roars like a jet engine for a few seconds to a minute, then I hear a burble in the gas line and the flame drops to a flicker, then jumps back to a roar again. It does produce good heat, but the on-again-off-again flame bothers me. It never has gone completely out, just drops back to idle. Here's a photo of the flame with a hammer head in the forge. Quote Link to comment Share on other sites More sharing options...
Frosty Posted March 28, 2016 Share Posted March 28, 2016 How about a pic of the entire forge including the burners from the side. That way we can get an idea of the layout and what kind of dragon's breath it's producing. Intermittent flames tend to have a couple general causes but it's hard to tell. Your description of the problem can't be happening. If you were actually hearing a burble in the GAS LINE it'd be spitting liquid propane and you'd mention the BIG fireballs shooting out the openings. It's just a matter of getting the jargon into your playbook, we all have to or we'd never know what we were talking about. I'm not familiar with the "Guru's" burners, I haven't visited that forum since my accident so that doesn't tell me much. Like I say pics from the side will help a lot. What this pic shows looks the flame being pretty good. Closing the opening down will REALLY help keep the heat inside where you need it. Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
jcornell Posted March 28, 2016 Share Posted March 28, 2016 A common problem with this design of forge is that if you don't stuff some sort of insulation into the burner holder, the holder acts like a chimney, exhausting hot gas right into the air intake of your burner. The hot gas has very little oxygen, so your burner sputters. I call it "huffing" because that's what it sounds like to me. Any design with the burner at Top Dead Center may have this problem if the exhaust gasses are going into the burner's air intake. I'm on forge #5. Forges 1 and 2 were of this design. Enjoy the journey. Quote Link to comment Share on other sites More sharing options...
olfart Posted March 28, 2016 Author Share Posted March 28, 2016 Frosty, I'll have to wait until tomorrow evening to get a side photo with dragon's breath. The forge is in an open shed, and daylight makes the dragon's breath hard to see. The burner is a 3/4" black pipe with 1 1/2" to 3/4" bell reducer on top with 1/8" pipe welded to a support in the middle of the opening. It has a .040 mig tip attached via 1/4" compression fitting. The propane tank is nearly empty (about 1.5" of frost at the bottom of the tank), and that may have a bearing on the inconsistency. And actually, the burbles in the gas line may be spitting fireballs, but the roaring stops momentarily. The fireballs may be hard to see in daylight. Jcornell, the fit between the burner support plate and the burner tube is pretty snug. I may have to try and find something to stuff in the support tube around the burner and see if that helps. Quote Link to comment Share on other sites More sharing options...
swedefiddle Posted March 28, 2016 Share Posted March 28, 2016 Good Morning, If your Propane Bottle is freezing up, sit it in another container of water. The water will act as a heat sink and slow down the freezing. If you connect two bottles in parallel, the draw from each bottle is in half, it will take a lot longer to freeze up. Propane is a liquid, the surface area of the liquid makes the Gas. Surface area frozen = No Gas. Neil Quote Link to comment Share on other sites More sharing options...
Frosty Posted March 28, 2016 Share Posted March 28, 2016 Okay, a 0.040" mig tip is on the large size that's why the flame looked on the rich side. I wasn't going to say anything from just the one pic but that's a larger jet than I put in a 3/4 T burner and they're better inducers so can support a larger gas jet. If you're getting frost on the tank you need to fill it, probably switch to a 40lb. and put it in a water bath to keep it from freezing. Be sure to strap it so it can't fall over flat you do NOT want to get liquid propane squirting into the forge. I think that's it for now, try switching for a 0.030" mig tip and a full tank in a water bath. More pics. Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
olfart Posted March 28, 2016 Author Share Posted March 28, 2016 I bought the .030 tips today but forgot that I'd have to have a new ferrule to install the new tip. One more trip to the hardware store tomorrow! In the meantime, I shot a couple more photos this afternoon. Quote Link to comment Share on other sites More sharing options...
olfart Posted March 29, 2016 Author Share Posted March 29, 2016 OK, I went back out after dark this evening and got a couple of shots of the dragon breath. I noticed some tiny sparks coming out the door, and I actually caught one of them in one of the photos. The burner is working MUCH better with a full tank of propane, I'm happy to note. . Quote Link to comment Share on other sites More sharing options...
jjhend28 Posted March 29, 2016 Share Posted March 29, 2016 I had this issue on a propane forge I built a while ago, part of it was that the AF burner I built needed to be run at such a high PSI that the tank had freezing issues causing the flame to die off and come back like that, when I sunk the tank in a bucket of warm water it fixed the issue some, The real fix was upgrading to a larger tank that could keep up with the demands of the burner. The other issue I had was already mentioned, oxygen depleted air was being sucked into the burner because it was vertical right above the forge. I hope this helps some. Quote Link to comment Share on other sites More sharing options...
olfart Posted March 29, 2016 Author Share Posted March 29, 2016 The intermittent burner problem appears to have been solved by filling the tank. There does not appear to be any hot air leaking back up the burner support tube, as I made a file-to fit opening in the support plate for the burner tube. Quote Link to comment Share on other sites More sharing options...
olfart Posted March 29, 2016 Author Share Posted March 29, 2016 I got the .030 MIG tip installed today, and the flame is now a warmer blue (no more green). I don't have a gauge on the regulator to tell me how much pressure, but I did lower the pressure significantly with no ill effects on the flame. Quote Link to comment Share on other sites More sharing options...
Frosty Posted March 29, 2016 Share Posted March 29, 2016 That's a much better looking flame, though maybe still a little rich. Is there a way you can pull the tip of the jet higher in the air intake? The farther from the tube's end the more air it will induce. I tune my burners by altering the distance the the jet is from the beginning of the burner tube. Most guys have their jets much deeper, some actually IN the tube and they end up running smaller jets. The spark is just a little dust, probably from a brick getting blown out, doesn't mean a thing. Now try closing off the door some and keep that burning propane IN the chamber. The longer the fire is in the box the hotter it will get, that blue flame coming out the opening is BTUs and $ you aren't getting to play with. Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
olfart Posted March 29, 2016 Author Share Posted March 29, 2016 I might could cut 1/4" off the back end of the tip, that would bring it back 1/4". Unfortunately with this burner design the tube is welded to the centering bracket, so there's no more adjustment. I looked for another 1 1/2" fitting today that I could use to make another burner, but no luck at the lumber yard. I'll probably have to go to a plumbing shop in Texarkana (35 mile drive) to find one. I'll try to get another dragon's breath photo tonight with the .030 tip. Quote Link to comment Share on other sites More sharing options...
Frosty Posted March 29, 2016 Share Posted March 29, 2016 How are you connecting the mig tip? I've never used a ferrule fitting, I just thread the ID of brass 1/8" pipe fitting the same as the mig contact tips. Another thought would be to use a 3/4" x 2" bell reducer for the intake. I haven't looked in a while but I don't recall Ron ever using a nipple to extend the depth of the intake. I could be wrong it's certainly become popular but it looks like a crutch for not being able to get it right. Have you followed Ron Reil's original plans? Before you try rebuilding a linear too much take a look at my T burner plans I made them as easy to follow as I could and a T is a LOT easier to build. Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
olfart Posted March 30, 2016 Author Share Posted March 30, 2016 Here's a pic of the dragon's breath tonight with the .030 tip. It's virtually invisible tonight. Quote Link to comment Share on other sites More sharing options...
Frosty Posted March 30, 2016 Share Posted March 30, 2016 Just a wisp of dragon's breath, nice. Is it getting hotter? Stand a brick on edge and block about 3/4 of the opening, that'll pep her up for you. Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
olfart Posted March 30, 2016 Author Share Posted March 30, 2016 OK, so if this is what it should look like, I'm good to go. Yes, it does seem to be hotter. With the .040 tip the flame was cooling down the center of the floor (dark spot in the center). The .030 tip heats the floor very well in the center. Thanks for your patience and help! Quote Link to comment Share on other sites More sharing options...
Frosty Posted March 30, 2016 Share Posted March 30, 2016 Your willingness to listen and try suggestions makes it a pleasure to be able to help. You're welcome. Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
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